1. Field of the Invention
The present invention relates to a circuit arrangement for monitoring the state of signal systems, particularly traffic light signal systems, with a comparator device which allows actual signal state respectively delivered by signal transmitters to be compared with the prescribed test signal states and with an evaluation device to which the clock pulse sequence is supplied only upon determination of allowable actual signal states and which indicates the presence of a disruption upon the determination of unallowable actual signal states.
2. Description of the Prior Art
A circuit arrangement of the type generally described above is already known in the art, for example from the periodical "Strassenverkehrstechnik", No. 2, 1972, pp. 39-43. In this known circuit arrangement, a comparator device is constructed of a plurality of logic circuits which are connected with the signal transmitters by fixed wiring. With the assistance of these permanently wired logic circuits, the signal states of the signal transmitters are then compared with so-called "hostile" signal images. If a coincidence of the actually existing signal states, i.e. the actual signal states of the signal transmitter concerned with such a predetermined signal image, then the signal state is evaluated in a corresponding signal safety device as an erroneous state. It is thereby disadvantageous that, as a result of the individual wiring corresponding to the conditions respectively existing, a rearrangement or, respectively, expansion of such a circuit arrangement to adapt to new or, respectively, changed conditions, can only be undertaken with great difficulty.